Electric attachment-plug.



4 s. W. ITO ELEGTBI G ATTACHMENT PLUG. AIIZLIOATION FILED MAR. 18,1909.

Patented Oct. 26,1909,

wasi WITNESSES lNVBNTOR ATTORNEY UNITED STATES PATENT OFFICE.

SEYKICHI W. I'I'O, OF SAN FRANCISCO, CALIFORNIA.

ELECTRIC ATTACHMENT-PLUG.

Specification of Letters Patent.

Patented Oct. 26, 1909.

Application filed March 18, 1909. Serial No. 484,300.

of twisting the pair of conducting .cords which are attached to it andare used to conduct current from the socket to its place of use.

A further object is to provide a plug of this character through whichthe circuit will be closed only when the plug is fully connected to thesocket.

In the accompanying drawing, Figure 1 is a side view of the plug, theparts being in the position in which the plug is not connected to thesocket; Fig. 2 is a sectional view, the parts being in the position inwhich the plug is connected; Fig. 3 is a sectional view-= on-line 33 ofFig. 2; Fig. 4c is a horizontal section on the line 4-4 of Fig. 3; Fig.5 is a horizontal section on the line 55 of Fig. 2; Fig. 6 is a detailperspective view of the contact shell of the plug.

Referring to" the drawing, 1 indicates a hlock of porcelain or othersuitable insulating material, havlng a reduced cylindrical upper portion2, surrounding which is a contact shell 3. Said shell is formed with adepending tongue 4, which extends into a hole 5 in the lower enlargedportion 6 of the block 1, and thus serves to hold the shell firmly onthe reduced portion of the block. Said shell is formed of spring metal,and has cut therefrom three tongues 7, 8, at equal angular distances onefrom the other, of which the two tongues 7 are longer than the tongue 8,all of said tongues being united at their lower ends to the shell andnormally projecting therefrom. Therefore they are adapted to contactwith the inner surface of an electric lamp socket, and hold the plug inthe socket by spring pressure. Arranged vertically in a bearing-1n saidblock 1 is a shaft 9, the upper end of which carries a cam 10 extendingthrough a lateral opening inthe side of the reduced portion 20 of theplug, which cam, when the shaft 9 is rocked, bears against the shortertongue 8 and presses it outward, thus causing it to firmly engage theside of the lamp socket and hold the plug therein. Upon the lower end ofsaid rock shaft is secured a crank arm 11, extending through a slot 12in the lower casing 13 of the plug, said crank arm being adapted, whenthe shaft 9 is rocked, to engage spring clips 14, which then, hold thecrank arm in the position to which it has been rocked, in which positionthe plug is securedin the socket by means of the cam 10.

Of the conducting cords, one, the cord 15, passes to a binding screw 16,which is connected by a bolt 17 through the insulating block l'with theplate 18 in a recess 19 therein, to which plate is secured a spring 20having a head 21 adapted to engage the central 1 contact of the electriclamp socket. The

other conducting wire is connected by a binding screw 22 to the springclips 14. The c1rcuit through this wire is therefore closed only whenthe crank arm 11 has been shifted to the position securing the plug inthe socket, the current then passing through said spring clips 14, thecrank arm 11, rock,

shaft 9, and cam 10, to the cylindrical contact shell 3, which is incontact with the cylindrical contact surface of the lamp socket.

In use, the plug is inserted in the socket without twisting and thecrank arm is again moved to the right so as to engage the sprin clips.The plug is then securely fastene in the socket. To disconnect the plug,the crank armis moved to the left, which breaks the circuit through theconducting wires, and relieves the pressure upon the cylindrical surfaceof the lamp socket, and the plug is then withdrawn.

I claim':

An attachment plug for lamp sockets comprising an insulatmg plug havinga reduced portion, a contact shell around said reduced portion having atongue out therefrom, a

.Q I I w 938,288 I I i i X when the cam has been moved to so project Intestimony whereof'I have hereunto set stantially as described. I

" said tongue, a spring arranged. centrally of my. hand in the presenceof two subscribing said plug, a contact head carried thereby wltnesses.

- and two conductingvwires, one ofwhich Is velectrically connected tosaid. sprin and the Witnesses:

vSE YKICI-I I- we r120.

"-ps, sub= Dnnsols H IJLZFRANOIS M. RIGHT.

other is connected to said contact

